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Page 1: Forecasting Exchange Rates - RWI Essen · Forecasting Exchange Rates: The Time-Varying Relationship between Exchange Rates and Taylor Rule Fundamentals Abstract There is empirical

RUHRECONOMIC PAPERS

Forecasting Exchange Rates: The Time-Varying Relationship between Exchange Rates and Taylor Rule Fundamentals

#704

Ulrich Haskamp

Page 2: Forecasting Exchange Rates - RWI Essen · Forecasting Exchange Rates: The Time-Varying Relationship between Exchange Rates and Taylor Rule Fundamentals Abstract There is empirical

Imprint

Ruhr Economic Papers

Published by

RWI Leibniz-Institut für Wirtschaftsforschung Hohenzollernstr. 1-3, 45128 Essen, Germany

Ruhr-Universität Bochum (RUB), Department of Economics Universitätsstr. 150, 44801 Bochum, Germany

Technische Universität Dortmund, Department of Economic and Social Sciences Vogelpothsweg 87, 44227 Dortmund, Germany

Universität Duisburg-Essen, Department of Economics Universitätsstr. 12, 45117 Essen, Germany

Editors

Prof. Dr. Thomas K. Bauer RUB, Department of Economics, Empirical Economics Phone: +49 (0) 234/3 22 83 41, e-mail: [email protected]

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Prof. Dr. Volker Clausen University of Duisburg-Essen, Department of Economics International Economics Phone: +49 (0) 201/1 83-3655, e-mail: [email protected]

Prof. Dr. Roland Döhrn, Prof. Dr. Manuel Frondel, Prof. Dr. Jochen Kluve RWI, Phone: +49 (0) 201/81 49-213, e-mail: [email protected]

Editorial Office

Sabine Weiler RWI, Phone: +49 (0) 201/81 49-213, e-mail: [email protected]

Ruhr Economic Papers #704

Responsible Editor: Volker Clausen

All rights reserved. Essen, Germany, 2017

ISSN 1864-4872 (online) – ISBN 978-3-86788-818-9The working papers published in the Series constitute work in progress circulated to stimulate discussion and critical comments. Views expressed represent exclusively the authors’ own opinions and do not necessarily reflect those of the editors.

Page 3: Forecasting Exchange Rates - RWI Essen · Forecasting Exchange Rates: The Time-Varying Relationship between Exchange Rates and Taylor Rule Fundamentals Abstract There is empirical

Ruhr Economic Papers #704

Ulrich Haskamp

Forecasting Exchange Rates: The Time-Varying Relationship between Exchange

Rates and Taylor Rule Fundamentals

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Bibliografische Informationen der Deutschen Nationalbibliothek

Die Deutsche Bibliothek verzeichnet diese Publikation in der deutschen National-bibliografie; detaillierte bibliografische Daten sind im Internet über: http://dnb.d-nb.de abrufbar.

Das RWI wird vom Bund und vom Land Nordrhein-Westfalen gefördert.

http://dx.doi.org/10.4419/86788818ISSN 1864-4872 (online)ISBN 978-3-86788-818-9

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Ulrich Haskamp1

Forecasting Exchange Rates: The Time-Varying Relationship between Exchange Rates and Taylor Rule Fundamentals

AbstractThere is empirical evidence for a time-varying relationship between exchange rates and fundamentals. Such a relationship with time-varying coefficients can be estimated by a Kalman filter model. A Kalman filter estimates the coefficients recursively depending on the prediction error of the examined model. Using a Taylor rule based exchange rate model, which in the literature was found to have promising forecasting abilities, it is possible to further improve the performance if the utilization of information from the prediction error is restricted. This is necessary as classic exchange rate models do not perform badly solely because they neglect the time-varying relationship, but also due to missing explanatory information. So, if the Kalman filter uses the entire information from the prediction error, it would overestimate the need for coefficient adjustment. With this calibration of the Kalman filter model the short-term out-of-sample forecasting accuracy can be enhanced for 10 out of 12 exchange rates.

JEL Classification: C53, F31, F37

Keywords: Exchange rates; forecasting; Kalman filter; state space models

July 2017

1 Ulrich Haskamp, RGS Econ and UDE. – All correspondence to: Ulrich Haskamp, University of Duisburg Essen, Universitätsstr. 12, 45117 Essen, Germany, e-mail: [email protected]

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1. Introduction

Exchange rates are important for many economic agents. Currencies need to be exchan-

ged when goods are traded across borders, investors finance projects abroad and emigrants

send parts of their wage home. In an increasingly globalized world this is of particular

importance. However, all these economic agents face exchange rate risks. The costly con-

sequences of these risks could be mitigated by reliable exchange rate forecasts. Performing

reliable exchange rate forecasts is, however, one of the puzzles of the economics profession.

Meese & Rogoff (1983) found in their seminal paper that classic exchange rate models were

not able to forecast better than a naive random walk. Cheung et al. (2009) confirmed this

finding for newer models and a longer sample.

A possible reason for the non-satisfactory performance of economic exchange rate mo-

dels is that the relationship between exchange rates and their fundamentals varies over

time and it is strongly influenced by expectations and uncertainty (Rossi, 2013; Beckmann

& Czudaj, 2017a,b,c). For example, if the output of a country decreases by just a small

amount, this has generally not a strong impact on the exchange rate. In times of recession,

however, the impact is likely to be larger than usual. Another reason for a time-varying

relationship is provided by the scapegoat model of Bacchetta & Wincoop (2004). In such

a model the exchange rate can change due to unobservable factors such as non-speculative

trading but investors attribute this change to other observable explanatory variables which

increases their impact on the exchange rate.

Furthermore, empirical evidence for such a relationship can be found in the literature.

Fratzscher et al. (2015) tested the aforementioned scapegoat theory empirically using sur-

vey data of about 50 foreign exchange investors who were asked about their individual

weighting of the importance of various fundamentals for 12 currencies. Additionally, they

obtained order flow data from the UBS, a major player in the foreign exchange market, to

model the unobservable factors that drive exchange rates. They found that the in-sample

performance of an exchange rate model for the period of 2001-2009 including this time-

varying weighting and the unobservable factors improves substantially for all examined

currency pairs. Further in-sample evidence is provided by Beckmann et al. (2011), who

confirmed that the relationship between the German mark/euro-US dollar exchange rate

and its fundamentals incorporates breaks and depends on different fundamentals over time.

Out-of-sample evidence is provided by Sarno & Valente (2009). They show, using a rolling

forecasting exercise, that the best model to forecast exchange rates consists of frequently

4

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changing fundamentals. In this paper we estimate a time-varying relationship and use it

then for out-of-sample forecasting as done by Rossi (2006).

For the underlying exchange rate model, a Taylor rule based model which was found

to have promising out-of-sample forecasting abilities for the short-term is used (Rossi,

2013). Additionally, contrary to Meese and Rogoff (1983), true out-of-sample forecasts are

performed. True out-of-sample forecasts mean that no rational expectations about future

realizations of the explanatory variables are needed, and only lagged variables are used.

Taylor rule models were first used for forecasting by Molodtsova & Papell (2009). They

evaluated such models as more useful than classic exchange rate models as the purchasing

power parity or the monetary approach. A time-varying relationship can be inserted into

the models using a Kalman filter. The Kalman filter approach is chosen for two reasons:

Firstly, this framework allows for continuously changing coefficients which are not restricted

to certain historical or recurring values. Secondly, a stochastic component is embedded.

Those features justify our choice ahead of other techniques such as Markov switching or

smooth transition models. As in Schinasi & Swamy (1987), Wolff (1987), Ng & Heidari

(2008) or Rossi (2006), it is assumed that the coefficients of the exchange rate model behave

like random walks and evolve over time. The Kalman filter allows a recursive estimation

of the unobservable time-varying variation in the coefficients. Using an updated version

of the data set of Molodtsova & Papell (2009), it is then tested whether this modification

improves the forecasting performance compared to the baseline model.

The starting point for our calibration of the Kalman filter is Rossi (2006). The coef-

ficients are assumed to behave as a random walk. The evolution of the time-varying

coefficients is slowed down by introducing a parameter smaller than one into the state

equations’ error term of the Kalman filter model. Our newly introduced feature is that

also the considered prediction error, which usually is very high for exchange rate models

(Evans & Lyons, 2002), is reduced by incorporating another parameter lower than one into

the signal equation’s error term. So, if the performance of exchange rate models is weak not

only because of non-time-varying coefficients, but also due to missing information, then the

Kalman filter would overestimate the prediction error and thereby the need for coefficient

adjustment. With this calibration the short-term forecasting accuracy can be enhanced

for 10 out of 12 exchange rates. This favorable result is also robust against other window

sizes of the rolling regressions. This is interesting as for lower window sizes a time-varying

relationship is already more strongly implied for the baseline model. Comparisons against

the random walk without drift show, nevertheless, that the result of Meese & Rogoff (1983)

5

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prevails that the random walk cannot be beaten in exchange rate forecasting.

This paper’s contribution is to show that applying a time-varying coefficient approach

to Taylor rule exchange rate models can further improve the short-term out-of-sample fo-

recasting abilities compared to simple OLS forecasts. Using a very long sample, examining

12 different exchange rates and varying window sizes, the result is found to be robust.

However, this is only possible if one adjusts the calibration of the Kalman filter model

for the estimation of the underlying exchange rate model. This opposes the results of ol-

der papers such as Schinasi & Swamy (1987), Wolff (1987)) or Ng & Heidari (2008) who

found, using short samples of about 10 years, that a simple Kalman filter model is better

in forecasting exchange rates than OLS. Other authors such as Rossi (2006), using longer

and more recent samples, did not obtain such results. In our robustness chapter we also

find that the nearer we get to the standard calibration of the Kalman filter, the worse the

results become. Therefore, our new calibration adds value to the literature by showing

that a Kalman filter can be capable of improving exchange rate forecasts - also for more

recent data.

The outline of this work is as follows: In the first section the underlying Taylor rule

exchange rate model, as used by Molodtsova & Papell (2009), is stated. Secondly, it is

explained how time-varying relationships are incorporated into exchange rate models by

the Kalman filter model. After this, the criteria to evaluate the forecasting performance,

the data set and the forecasting methodology are described. Then, the results of a forecast

performance comparison between a Taylor rule exchange rate model including a time-

varying relationship and a benchmark model, either the baseline Taylor rule model of

Molodtsova & Papell (2009) or the random walk, are presented. Lastly, the robustness of

the previous results with regard to different window sizes of the rolling regressions and the

Kalman filter calibration is examined.

2. Taylor Rule Exchange Rate Model

The underlying exchange rate model for the forecast comparison between a model with

and without a time-varying relationship is Taylor (1993) rule based. Such Taylor rule

models have been applied to exchange rate economics by Engel & West (2005), Engel &

West (2006) or Mark (2009). Engel et al. (2007), Wang & Wu (2012) and Lansing & Ma

(2015) found that they are useful for exchange rate forecasting. Additionally, Molodtsova

et al. (2008), Molodtsova & Papell (2009) and Beckmann & Schussler (2016) noted that

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the influence of the included variables varies over time. Also, the Taylor rule model itself

has been estimated with a time-varying coefficient model. See Yuksel et al. (2013) for a

survey.

Taylor’s rule relies on the idea that a central bank sets its short-term key interest rate

as a function of inflation, targeted real key interest rate and output gap:

i∗t = πt + φ(πt − π∗) + γyt + r∗ (1)

An asterisk denotes the targeted level. This equation shows that the central bank raises

its key interest rate target, i∗, in case of inflation, π, rising above the targeted level. It also

sets the rate higher when the output gap, y, is increasing. Because it is assumed that the

target for the key interest rate is reached within one period, the actual interest rate is not

included (Mishkin, 2004).

From this basic equation, we can get the nominal interest rate reaction function assu-

ming that the central bank targets its currency’s purchasing power parity (PPP) to hold

and that adjustments to the interest rate are only done successively. For details refer to

Molodtsova & Papell (2009). So, the derived equation looks like the following:

it = (1− ρ)(μ+ λπt + γyt + δqt) + ρit−1 + vt (2)

The q represents the real exchange rate. For the United States δ is equal to zero because

it is the reference currency for all exchange rates examined later. To obtain an estima-

ble equation, the US interest rate reaction function is subtracted by its foreign country’s

counterpart:

it − it = α+ αuππt − αfππt + αuyyt − αfyyt − αq qt + ρuit−1 − ρf it−1 + ηt (3)

A tilde denotes a foreign variable. The indices u and f display coefficients of the US and

the foreign country, respectively. α is a constant, απ = λ(1 − ρ) and αy = γ(1 − ρ) for

both countries, and αq = δ(1− ρ) for the foreign one. The error term of this two-country

equation is denoted as η.

The effect of a successively adjusted interest rate can be explained in the following way:

If inflation rises, the central bank will increase the interest rate by (1− ρ)λΔπ in the first

period. In the second period, it will be raised by (1− ρ2)λΔπ and so forth. Note that ρ is

assumed to be between zero and one.

If one assumes uncovered interest rate parity (UIP), the interest rate differential is

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proportional to the expected exchange rate depreciation:

E(Δst+1) = ω(it − it) (4)

Inserting this equation into Equation (3) and assuming rational expectations, a Taylor rule

based exchange rate forecasting equation is gained:

Δst+1 = ω + ωuππt − ωfππt + ωuyyt − ωfyyt − ωq qt + ρuit−1 − ρf it−1 + ηt (5)

However, the literature shows that the UIP does not hold in the short run. Chinn (2006)

examines new empirical findings about the UIP and found that in the short-term the

interest rate differential is still a biased predictor of ex-post changes of exchange rates.

Cheung et al. (2009) found that the UIP can forecast exchange rates only in the long-

run. Recent carry trade literature, as Burnside et al. (2007), even suggests that the ω of

Equation (4) can be negative. Still, this equation can be used for forecasting if the signs

and values of the coefficients are not restricted.

Furthermore, Molodtsova & Papell (2009) made the prediction that an increase of the

interest rate results in exchange rate appreciation. Gourinchas & Tornell (2004) presented

a theoretical model in which the investors misperceive the persistence of an interest rate

change. This allows for a mechanism in which an increase of the interest rate leads to an

exchange rate appreciation. Additionally, they presented survey evidence which shows that

investors underestimate the persistence of interest rate shocks to support their theory.

If interest rate smoothing is assumed, higher inflation not only raises the current interest

rate but also leads to the expectation that the interest rate will continue to rise in the future.

Therefore, an increase of the inflation rate does result in immediate and expected future

exchange rate appreciation. A further effect of interest rate smoothing, in the context of the

Gourinchas & Tornell (2004) theory, is that investors are even more likely to underestimate

the true nature of the persistence of interest rate shocks because the initial change of the

interest rate is smaller than the total change over time. This strengthens the effect of

inflation on the exchange rate (Molodtsova & Papell, 2009).

Three additional predictions in the context of the Taylor rule are made by Molodtsova

& Papell (2009). Firstly, an increase in the US output gap leads to a rise of the interest rate

which then results in a depreciation of the exchange rate. Secondly, if the real exchange rate

depreciates, the foreign central bank will raise its interest rate to revert the real exchange

rate back to its PPP equilibrium. Lastly, assuming interest rate smoothing, a higher lagged

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interest rate leads to further immediate and expected future depreciation of the exchange

rate.

This Taylor rule forecasting equation can be used in several different specifications of

the variables on the right-hand side. Firstly, in his original paper Taylor (1993) stated for

Equation (3) that the central bank sets the nominal interest rate only according to the

inflation gap, the output gap and the equilibrium real interest rate omitting the lagged

interest rate differential and the real exchange rate. If the foreign central bank behaves

similarly, this model is called symmetric. However, following Clarida et al. (1998), it can

be assumed that the foreign central bank aims at the difference between the actual and

targeted exchange rate defined by PPP. In such an asymmetric model the real exchange

rate is included in the equation, ωq �= 0. Here, however, only symmetric models, for which

Molodtsova & Papell (2009) found the best predictability, are examined for conciseness.

Alba et al. (2015) examine asymmetric models for inflation-targeting emerging markets for

which the real exchange rate is likely to be an important determinant.

The next specification adds the lagged interest rate differential to the right-hand side

to account for a successively adjusted interest rate, as suggested by Clarida et al. (1998).

In this case the model is denoted as with smoothing, ρu, ρf �= 0, or otherwise as with no

smoothing.

Lastly, if both central banks respond equally to changes of the right-hand side variables

so that ωuπ = ωfπ, ωuy = ωfy and ρu = ρf , the model is called homogeneous. If they are not

identical, each appears solely on the right-hand side and the model is called heterogeneous.

Therefore, the models which are considered here are with or without smoothing and include

homogeneous or heterogeneous coefficients.

3. Modeling the Time-Varying Relationship

Section 1 outlined empirical evidence for a time-varying relationship between exchange

rates and fundamentals. In this section the estimation of such a relationship with a Kalman

(1960) filter model is described. Other authors, for example, Canova (1993), Carriero et al.

(2009) or Beckmann & Schussler (2016) used other models which allow for a time-varying

relationship. See Rossi (2013) for a further review.

First of all, a short introduction to a Kalman filter model is given. A Kalman filter

model is a state space model which consists of signal and state equations. The signal equa-

tion describes the relationship between the observed and unobserved variables. The state

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equations represent the evolution of the unobserved variables, here the time-varying coef-

ficients, βt. The Kalman filter recursively estimates the unobserved variables conditional

on the available information. With some chosen starting values the first signal equation

is estimated in t = 0. In t = 1 the prediction error is calculated by comparing the actual

dependent variable with the estimated one. This prediction error is then used to update

the beliefs about βt=0. Using the updated coefficient, the next signal equation is estimated

and so forth.

Kalman filter models with a time-varying relationship have already been used in ex-

change rate forecasting. Schinasi & Swamy (1987) allowed the coefficients of their monetary

exchange rate models to vary over time in the following way:

st = f ′tβt + εt (6)

βt = βt−1 + ηt (7)

ηt = φut−1 + νt (8)

E(νt) = 0 (9)

The first equation of this system is the signal equation with ft containing the explana-

tory variables. Equation (7) is the state equation which describes the development of the

coefficients. As the error term ηt of the state equation is assumed to be of autoregressive

order, the coefficients follow an autoregressive process. Comparing their forecasts with the

random walk, they found favorable results if a lagged dependent variable is included.

Wolff (1987) used the Kalman filter to estimate such a time-varying parameter model

for similar monetary models. Contrary to Schinasi & Swamy (1987), he assumed that the

coefficients behave as a random walk such that φ = 0. He found that this model is often

able to forecast more accurate than the random walk. However, a newer study by Rossi

(2006) was not able to obtain similar findings for autoregressive models, with or without

further economic variables, and a longer sample. Rossi (2013), giving an overview over

further studies, comes to the conclusion that the empirical evidence is mixed. Furthermore,

Bacchetta et al. (2010) conclude that time-varying parameters cannot explain the puzzle of

Meese & Rogoff (1983) which, though, is debated by Chinn (2009) and Giannone (2009).

Here the time-varying relationship between exchange rates and fundamentals is modeled

comparable to Wolff (1987) and Rossi (2006). However, it is newly applied to models with

10

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Taylor rule fundamentals for short-term forecasting and a longer sample.

Δst+1 = ω + ωuπ,tπt − ωfπ,tπt + ωuy,tyt − ωfy,tyt + ρu,tit−1 − ρf,tit−1 + εt (10)

ωcv,t = ωcv,t−1 + ηt for c = (f, u) and v = (π, y) (11)

ρc,t = ρc,t−1 + ηt for c = (f, u) (12)

This model can be formulated more concise:

Δst+1 = f ′tβt + εt (13)

βt = βt−1 + ηt (14)

where εt ∼ iid(0, κ2σ2ε ), ηt ∼ iid(0, λ2σ2

ηQ), E(ηtεt) = 0 and Q = E(ftf′t)

−1 ∀t and with

vector ft including the k fundamentals.

So, the Kalman filter is calibrated in the following way: Starting values for the coef-

ficients are set to zero for every regression. For all state equations the error terms are

assumed to be equal, and are normalized by a k × k covariance matrix which is specified

by Q = E(ftf′t)

−1. Furthermore, λ < 1 is the ratio between the variance of the signal

and state equations’ error terms. A smaller λ leads to a slower coefficient evolution. Till

now the calibration of the Kalman filter is the same as in Rossi (2006) or Stock & Watson

(1996).

The difference to previous approaches is that a parameter κ < 1 is inserted into the

signal equation’s error term. The effect is that the prediction error, Δst−Δst, which usually

is very high in exchange rate models (Evans & Lyons, 2002), has less of an effect on the

updating of the coefficients. If the bad performance of exchange rate models is not solely

due to non-time-varying coefficients, but also due to missing explanatory information, then

the Kalman filter would adjust the coefficients too strongly. Henceforth, κ is set to 0.001

and λ is set to κ · 0.1. The value of κ is chosen to be very small to ensure that only a

very limited amount of information of the prediction error is used. The value of λ is set

comparable to Rossi (2006) and slows the evolution of the coefficients down. In Section 7.1

it will be examined whether the upcoming results are robust to other calibrations of these

parameters. We refrain from adding further variables as it is already difficult for a Kalman

filter to estimate a model with 6 variables and account the information of the prediction

error towards a specific variable.

For the upcoming forecast exercise rolling regressions are used. See Section 5 for de-

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tails. Rolling regressions already implicitly allow coefficients to change at every step for-

ward. Molodtsova & Papell (2009) showed in their paper how the coefficients evolve across

their sample. Here it is shown that it is still worthwhile to use models which allow for

time-varying parameters in addition to rolling regressions. In Figure 1 the path of the

coefficients across the sample for rolling regressions estimated with OLS and a Kalman

filter is shown. For the Kalman filter model the final state values are reported. All equa-

tions are estimated for a symmetric Taylor rule model with smoothing and heterogeneous

coefficients for the Pound-US dollar exchange rate. In general, it can be seen that for

both estimation methods the coefficients follow a similar path, but the coefficients of the

Kalman filter model incorporate more abrupt adjustments. For further explanations about

the path of the coefficients we refer to Molodtsova & Papell (2009).

Figure 1: Estimated Coefficients of a Kalman Filter Model and OLS

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Recent studies also employed other methods to model the time-varying relationship.

See, for example, Fratzscher et al. (2015) who obtained actual data about the weighting

investors put on fundamentals. Finding favorable results, their sample is, however, too

short to conduct an out-of-sample forecasting exercise.

In this section the forecasting performance of the Taylor rule models will be examined

with a special focus on whether it is possible to improve forecasting by taking the time-

varying relationship between exchange rates and fundamentals into account.

4. Evaluating Forecasting Performance

The forecasting performance of the models is evaluated by calculating the mean squared

prediction error (MSPE). For a sample with T observations the MSPE of P forecasts is

calculated as follows:

σ2m = P−1

T∑

t=T−P

(em,t+1)2 (15)

Where em,t+1 is the one-period ahead forecast error of the respective model m. For the

random walk the forecast is that the exchange rate does not change, erw,t+1 = Δst+1. With

the Diebold-Mariano test (1995) it can be tested whether the MSPE of a model is different

from a competing model. The null hypothesis is that both models’ MSPE are equal which

is tested against the alternative that model m has a higher MSPE:

H0 : σ2m − σ2

n = 0 (16)

H1 : σ2m − σ2

n > 0 (17)

For the construction of the Diebold-Mariano (DM) test statistic, the average difference

between the forecast errors of the competing models is defined as:

f = P−1T∑

t=T−P

(em,t+1 − en,t+1) = σ2m − σ2

n (18)

Then the DM test statistic can be computed as follows:

DM =f√

P−1Vwith V = P−1

T∑

t=T−P

((em,t+1 − en,t+1)− f)2 (19)

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The denominator represents the standard error of the difference between the competing

models’ forecast errors. The test statistic of the Diebold-Mariano test can easily be gained

by regressing the difference of the forecast errors on a constant. To estimate the standard

error consistently, a Newey-West covariance estimator which is consistent in the presence

of both heteroskedasticity and autocorrelation is used (Elliot et al., 2006). For the cova-

riance estimator the lag length is chosen by the automatic bandwidth selection method

for kernel estimators of Newey-West (1994). Because the DM statistic is asymptotically

normal distributed, the resulting t-statistic of the regression can be used to test the above

mentioned hypothesis (Diebold & Mariano, 1995). Note that the DM test in this setup is

one-sided. Therefore, a significant and positive DM test statistic implies that model n out-

performs m because σ2m is significantly higher than σ2

n. The critical values for a one-sided

test and P → ∞ are 1.282, 1.645 and 1.960 for the significance levels 0.10, 0.05 and 0.01,

respectively.

Newer test statistics for a test which compares nested models also exist and were used,

for example, by Molodtsova & Papell (2009), Gourinchas & Rey (2007) or Engel et al.

(2007). In nested models, one model is contained within the other. This is, for example,

given for a comparison between the random walk and any other model. Note that this is not

the case if Taylor rule models with and without time-varying relationships are compared

as the models are different due to the time-varying coefficients. The tests of Clark & West

(2006, 2007) and Clark & McCracken (2001, 2005) compensate for the fact that the DM

test statistic is undersized under the null hypothesis when comparing nested models. In the

context of exchange rates, both tests take into account that, given the null hypothesis, the

exchange rate follows a random walk. However, as Rogoff and Stavrakeva (2008) showed,

these tests are no real minimum MSPE tests. Rather, they show if the true model is a

random walk instead of whether the random walk has a lower MSPE than the structural

model. So, a DM test compares models’ forecasting ability while the newer tests look

at predictability (Molodtsova & Papell, 2009). Thus, here the DM test is used for a

comparison between nested models.

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5. Data Set and Forecasting Methodology

The data used in this work was obtained from David Papell’s homepage and has been

updated. Besides the update it is the same as in Molodtsova & Papell (2009).1 It ranges, in

general, from March 1973 to December 1998 for the euro area countries and to May 2015 for

the others.2 Due to missing data, the sample starts in January 1975 for Canada, September

1975 for Switzerland and January 1983 for Portugal. The main source for the data is the

International Monetary Fund’s International Financial Statistics database.3 Because GDP

data is available only quarterly, a seasonally adjusted monthly industrial production index

is used for the calculation of the output gap. The economies’ price levels are measured

by the consumer price index and inflation is then calculated as the 12-month difference of

the price index. For the interest rates set by the central banks the corresponding money

market rates are taken. The exchange rates are obtained from the Federal Reserve Bank

of Saint Louis’ database.

For the construction of the output gap, a Hodrick & Prescott (1997) filter with the

standard smoothing parameter of 14,400 for monthly frequencies was used, with a sample

beginning in January 1971, to obtain the potential output. The output gap is then cal-

culated by the percentage deviation of the potential and actual output. Because rolling

regressions are used for forecasting, the output gap is recalculated for each step with data

excluding the forecasted month. So, no ex-post data is used for the calculation. Thereby,

it is simulated that the central bank’s decision to set the interest rate is based only on

the information available at that time. However, this only mimics real-time data because

revised data is still used. Another shortcoming is that it is not known how exactly the

central banks calculate the output gap for their decision making. For example, Orphanides

(2001), estimating Taylor rules for the USA, used output gap data generated by the US

central bank itself, but such data is not available for the full sample or other countries.

Nevertheless, Orphanides & van Norden (2002) stated that most of the difference between

revised and real-time data of output gap estimation comes from using ex-post data, not

from revisions.

1Compare www.uh.edu/œdpapell/papers2.htm.2The euro area currencies are French franc, German mark, Italian lira, Dutch guilder and Portuguese escudo.The others are Canadian dollar, Australian dollar, Danish kroner, Japanese yen, Swedish kronor, Swiss francand British pound.

3The only exception is that the German consumer price index is taken from the OECD Main EconomicIndicators database.

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With this data the Forecasting Equations (5) and (10) are estimated. The regressions

are then used for the one-month ahead forecasts of the exchange rates. As in Molodtsova

& Papell (2009), a sample of 120 observations is taken for the rolling regressions. Thus, the

first estimation is done with data from March 1973 until February 1983 and the exchange

rate is out-of-sample forecasted for March 1983. The out-of-sample forecast is done with

data for the explanatory variables excluding the forecast period contrary to Meese & Rog-

off (1983). Thus, rational expectations about their development are not needed and the

forecasts are truly out-of-sample. For the next estimation the first data point is dropped

and an additional one is added at the end of the sample. Then the next out-of-sample

forecast follows. So, the regressions roll over the full sample. The full sample, however,

differs for the countries. As previously mentioned, the euro area countries’ samples end

in December 1998 and data is missing for Portugal, Switzerland and Canada. So, for the

euro area exchange rates 190 instead of 388 forecasts are performed, for Portuguese, Swiss

and Canadian exchange rates only 72, 358 or 365, respectively. Note that also the output

potential is calculated again with each step, but the beginning of the sample is not dropped.

Because the various specifications for Equations (5) and (10) differ in their forecasting

performance, only symmetric specifications for which Molodtsova & Papell (2009) found

the best predictability are evaluated. First, the MSPE for each exchange rate is calculated.

Secondly, the Diebold-Mariano test statistic for a comparison between the model of Equa-

tion (10) and the benchmark model, which is either the random walk or the corresponding

model without a time-varying weighting, Equation (5), is determined.

Figure 2: Forecast Comparison between Equation (5) and (10) for the Pound-US Dollar Exchange Rate

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An example comparison between Equation (5) and (10) for a symmetric model with

interest rate smoothing of the Pound-US dollar exchange rate is shown in Figure 2. The

graph shows the difference between the forecast errors of both models. A positive value

represents that the model with a time-varying relationship has a smaller forecasting error.

The differences fluctuate around zero and it cannot be said that one model performs better

in certain periods.

6. Results

In this section the results of the forecasting equations are presented. The finding of

Meese & Rogoff (1983), or Cheung et al. (2009) for newer models and a longer sample,

which states that exchange rate models are not able to forecast better than a random

walk without drift which is the toughest benchmark to beat according to Rossi (2013) still

prevails. Therefore, the focus will be on whether including a time-varying relationship

between exchange rates and fundamentals improves the forecasting performance of Taylor

rule based exchange rate models. In Table 1 the MSPEs of symmetric specifications of

Equation (5) and Equation (10) with a time-varying relationship are presented.4 Symmetric

models do not include that the foreign central bank is targeting the real exchange rate.

A model denoted as smoothing incorporates the lagged interest rate. Furthermore, it

is necessary to distinguish between specifications with heterogeneous and homogeneous

coefficients. If a MSPE value is written in bold, then the model has a MSPE lower than

the random walk’s one. This is given for 7 of the 12 currency pairs. While for Italy most

models perform better than the random walk, this is only given for one of the time-varying

ones for Japan, Sweden and the United Kingdom. For five currencies no specification

forecasts better than the random walk. For all currency pairs, it cannot be generalized

that models with a time-varying relationship perform better. Additionally, no model is

able to significantly beat the random walk as can be seen in Table 2, which is comparable

to the findings of Rogoff and Stavrakeva (2008) for Taylor rule exchange rate models.

To evaluate whether there is a significant difference between the Forecasting Equati-

ons (5) and (10), Table 3 is presented. The signs of the DM test statistics vary across

4The following abbreviations are used henceforth in tables: Can for Canadian dollar, Aus for Australiandollar, Dan for Danish kroner, Fra for French franc, Ger for German mark, Ita for Italian lira, Jap forJapanese yen, Dut for Dutch guilder, Por for Portuguese escudo, Swe for Swedish kronor, Swi for Swissfranc and UK for British pound.

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Table 1: MSPE of Symmetric Specifications of Forecasting Equations (5) and (10)

Specification Can Aus Dan Fra Ger Ita

NoSmooth.

Heterog. Baseline 1.63 2.76 2.67 2.78 2.92 2.70Time-varying 1.62 2.76 2.63 2.69 2.84 2.64

Homog. Baseline 1.63 2.76 2.59 2.61 2.84 2.61Time-varying 1.62 2.73 2.57 2.61 2.79 2.61

Smooth. Heterog. Baseline 1.61 2.78 2.67 2.84 2.94 2.81

Time-varying 1.63 2.74 2.65 2.71 2.86 2.68Homog. Baseline 1.61 2.78 2.63 2.63 2.87 2.65

Time-varying 1.61 2.73 2.58 2.65 2.81 2.63

Random Walk 1.58 2.71 2.55 2.64 2.75 2.66

Specification Jap Dut Por Swe Swi UK

NoSmooth.

Heterog. Baseline 2.75 2.78 2.33 2.70 2.92 2.56Time-varying 2.72 2.76 2.36 2.63 2.91 2.46

Homog. Baseline 2.72 2.77 2.33 2.65 2.77 2.46Time-varying 2.71 2.74 2.30 2.60 2.78 2.44

Smooth. Heterog. Baseline 2.73 2.85 2.45 2.71 3.01 2.53

Time-varying 2.71 2.77 2.39 2.59 2.95 2.46Homog. Baseline 2.69 2.80 2.38 2.74 2.80 2.48

Time-varying 2.67 2.75 2.31 2.54 2.82 2.43

Random Walk 2.68 2.75 2.33 2.56 2.74 2.43

Notes: The table reports the MSPE for symmetric specifications of the baseline Equation (5)and (10) with a time-varying relationship. The values were calculated by forecasts for themonths March 1983 to December 1998 for euro area currencies and to May 2015 for the ot-her ones. Bold values denote that the model has a lower MSPE than the random walk.

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Table 2: DM Statistics for MSPE Comparisons between Symmetric Specifications of Forecasting Equations(5) and (10) Against the Random Walk

Specification Can Aus Dan Fra Ger Ita

NoSmooth.

Heterog. Baseline -1.51 -0.75 -2.48 -1.73 -1.78 -0.61Time-varying -1.26 -1.23 -1.75 -0.96 -1.65 0.22

Homog. Baseline -1.96 -1.53 -1.40 0.49 -1.24 0.87Time-varying -2.06 -0.41 -0.76 0.72 -1.37 0.92

Smooth. Heterog. Baseline -0.90 -0.91 -3.95 -2.00 -1.91 -1.26

Time-varying -1.25 -0.51 -1.75 -0.93 -1.24 -0.24Homog. Baseline -1.46 -1.65 -2.20 0.05 -1.31 0.10

Time-varying -1.14 -0.53 -0.86 -0.26 -1.56 0.41

Specification Jap Dut Por Swe Swi UK

NoSmooth.

Heterog. Baseline -1.17 -0.51 0.06 -2.09 -2.87 -1.82Time-varying -0.73 -0.31 -0.43 -1.65 -3.29 -0.41

Homog. Baseline -1.16 -0.59 -0.03 -2.71 -0.96 -0.75Time-varying -0.86 0.23 1.28 -1.40 -2.36 -0.25

Smooth. Heterog. Baseline -0.71 -1.32 -0.73 -2.46 -3.52 -1.05

Time-varying -0.45 -0.33 -0.46 -0.40 -4.20 -0.44Homog. Baseline -0.02 -0.89 -0.41 -2.48 -1.89 -1.03

Time-varying 0.30 0.00 0.46 0.50 -2.93 0.06

Notes: The table reports the DM statistics for a test of the equality of forecast accuracy for sym-metric specifications of the baseline Equation (5) and (10) with a time-varying relationship againstthe random walk. The values were calculated by forecasts for the months March 1983 to Decem-ber 1998 for euro area currencies and to December 2013 for the other ones. The critical valuesfor P → ∞ are 1.282, 1.645 and 1.960 for the significance levels 0.10, 0.05 and 0.01, respectively.

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currency pairs and Taylor rule model specifications, but are in general positive. Recall

that the critical values for a one-sided test and P → ∞ are 1.282, 1.645 and 1.960 for the

significance levels 0.10, 0.05 and 0.01, respectively. Therefore, the time-varying Taylor rule

model outperforms the baseline one for 10 of the 12 currencies. For two currency pairs

no significant statistic was obtained. Furthermore, as the MSPE is sensitive to outliers,

we also use another criterion to evaluate our forecast. The mean absolute error (MAE)

incorporates no squared loss function and is thus more robust to outliers. We show the

results for this criterion in Table 4. The results are only slightly weaker as we can improve

forecasting only for 9 out of 12 currencies. In these first results it is shown that estimating

a Taylor rule exchange rate model with a Kalman filter to take time-varying coefficients

into account can improve the forecasting accuracy. Nevertheless, these improvements are

not strong enough to beat the random walk so that the result of Meese & Rogoff (1983)

prevails.

Table 3: DM Statistics for MSPE Comparisons between Different Specifications of Forecasting Equations(5) and (10)

Symmetric Can Aus Dan Fra Ger Ita

No Smooth. Heterog. 0.44 0.01 0.75 1.40 1.38 1.16Homog. 0.58 1.62 1.21 -0.13 0.91 0.08

Smooth. Heterog. -0.44 1.02 0.40 2.33 1.59 1.82Homog. 0.29 1.71 1.82 -0.45 0.75 0.26

Symmetric Jap Dut Por Swe Swi UK

No Smooth. Heterog. 1.28 0.52 -0.55 0.92 0.27 2.79Homog. 0.37 0.86 0.67 2.17 -0.78 1.44

Smooth. Heterog. 1.39 2.15 0.99 1.51 1.31 1.33Homog. 0.56 1.05 0.64 1.80 -0.69 2.59

Notes: The table reports the DM statistics for a test of the equality of forecast accuracy for sym-metric specifications of the baseline Equation (5) and (10) with a time-varying relationship againstthe random walk. The values were calculated by forecasts for the months March 1983 to Decem-ber 1998 for euro area currencies and to December 2013 for the other ones. The critical valuesfor P → ∞ are 1.282, 1.645 and 1.960 for the significance levels 0.10, 0.05 and 0.01, respectively.

7. Robustness

This section details the robustness of the previously presented results. Some of the

robustness issues Rossi (2013) mentioned for exchange rate studies are already dealt with

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Table 4: DM Statistics for MAE Comparisons between Different Specifications of Forecasting Equations(5) and (10)

Symmetric Can Aus Dan Fra Ger Ita

No Smooth. Heterog. 0.11 1.19 1.29 1.42 1.24 1.41Homog. -0.01 2.86 0.24 -0.19 0.77 0.19

Smooth. Heterog. -0.23 2.38 0.79 2.56 1.91 2.96Homog. -0.13 2.55 1.36 -0.40 0.45 0.60

Symmetric Jap Dut Por Swe Swi UK

No Smooth. Heterog. 1.02 1.67 -0.87 1.09 -0.61 2.93Homog. 0.53 0.65 0.42 1.87 -1.53 0.00

Smooth. Heterog. 1.11 3.07 0.46 1.91 0.03 1.46Homog. 0.54 1.38 0.17 2.70 -1.47 1.56

Notes: The table reports the DM statistics for a test of the equality of forecast accuracy for sym-metric specifications of the baseline Equation (5) and (10) with a time-varying relationship againstthe random walk. The values were calculated by forecasts for the months March 1983 to Decem-ber 1998 for euro area currencies and to December 2013 for the other ones. The critical valuesfor P → ∞ are 1.282, 1.645 and 1.960 for the significance levels 0.10, 0.05 and 0.01, respectively.

as 12 different exchange rates and a very long sample are examined. Nevertheless, issues

such as the calibration of the Kalman filter model or the rolling regressions’ window size

remain to be examined.

7.1. Calibration of the Kalman Filter Model

In this section an alternative calibration of the Kalman filter model will be examined.

Recall the Kalman filter model of Section 3:

Δst+1 = f ′tβt + εt (20)

βt = βt−1 + ηt (21)

where εt ∼ iid(0, κ2σ2ε ), ηt ∼ iid(0, λ2σ2

ηQ), E(ηtεt) = 0 and Q = E(ftf′t)

−1 ∀t and with

vector ft including the k fundamentals.

Now, it is looked at the case where κ is increased to a value of 0.1 and λ remains as

κ · 0.1. Thus, we use more information of the prediction error of the model. The results

for this modified Kalman filter model are not presented as it can be said in general that

it now performs worse than the baseline OLS model for all exchange rates. To examine

the reasons for this, Figure 3 shows how the final state estimates for the Pound-US dollar

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exchange rate change due to this adjustment of the error term. It can be seen that the

final state coefficient estimates of the adjusted Kalman filter model, drawn in green, have a

larger variance than the baseline Kalman filter or OLS ones. This is in particular the case

for the years between 1995 and 2003. This shows that if the Kalman filter model uses a

higher share of the prediction error as information for the updating of the coefficients, then

the estimates get out of hand. The problem gets worse if κ is further increased. Setting κ

smaller than in the baseline Kalman filter model alters the results only slightly. Changes

of λ have no significant impact.

Figure 3: Coefficients Estimated with Different Kalman Filter Models or OLS

The previous paragraph showed that using too much information of the prediction error

leads to worse results. A reason for this can be that the Kalman filter cannot distinguish

whether the model performs badly because of a constant relationship between exchange

rates and fundamentals, or missing explanatory information. Compare for example the

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order flow model of Evans & Lyons (2002). If the bad performance is mainly due to the

latter, then the Kalman filter should not use the entire information of the prediction error

to estimate the time-varying coefficients.

7.2. Window Size of the Rolling Regressions

In the exchange rate forecasting literature window sizes are often chosen arbitrarily.

For example, Meese & Rogoff (1983) used a window of 93 observations for monthly data,

Molodtsova & Papell (2009) took 120 observations, and Gourinchas & Rey (2007) used

104 for quarterly data, while Cheung et al. (2009) took 42 and 59. This can lead to two

shortcomings. Firstly, the ad hoc chosen window may not find a significant difference

between the forecasting ability of the competing models, though it exists for shorter or

longer window sizes. Secondly, the researcher could compare models for different window

sizes until he finds satisfactory results. Addressing the first point, Inoue & Rossi (2012),

using the same data and methodology as Molodtsova & Papell (2009), found improved

evidence for predictability at smaller windows.

To analyze whether the favorable results of the baseline Kalman filter model are robust

to the chosen window size of the rolling regressions, the regressions were estimated for

windows between 48 and 120. For comparability, the sample is held constant across window

sizes although a shorter window would allow using a longer sample. The starting and

ending points of the window sizes are chosen such that between 4 and 10 years of data are

incorporated in the regressions.

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Figure 4: MSPE across Different Window Sizes of Equations (5) and (10) for the Pound-US Dollar ExchangeRate

The results across different window sizes for the Pound-US dollar exchange rate can

be seen in Figure 4. The MSPE of different specifications of Equations (5) and (10) are

grouped in one graph. The Kalman filter model’s MSPE is drawn in red. For all groups it

can be said that smaller window sizes lead to slightly higher MSPE. To get a clearer view,

the DM statistics for a comparison between Equations (5) and (10) are also shown for the

Pound-US dollar exchange rate in Figure 5. Lines are drawn in the graphs at -1.282 and

1.282 for the 10% significance levels of the DM statistic. While for the right hand models

the previous observation holds, it is less clear for the left hand side ones. Therefore, a

comparison of Equations (5) and (10) depends substantially on the chosen window size.

The figures, only for the non-euro countries to save space, can be found beginning with

Figure 5 in the following. In general, the favorable results for the Kalman filter are robust to

the choice of the window size, and for some currencies and specifications even strengthened.

This result is particularly interesting as for lower window sizes a time-varying relationship

is already more strongly implied for the baseline model.

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Figure 5: DM Statistics across Different Window Sizes of Equations (5) and (10) for the Pound-US DollarExchange Rate

Figure 6: DM Statistics across Different Window Sizes of Equations (5) and (10) for the Canadian Dollar-USDollar Exchange Rate

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Figure 7: DM Statistics across Different Window Sizes of Equations (5) and (10) for the Australian Dollar-US Dollar Exchange Rate

Figure 8: DM Statistics across Different Window Sizes of Equations (5) and (10) for the Danish Kroner-USDollar Exchange Rate

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Figure 9: DM Statistics across Different Window Sizes of Equations (5) and (10) for the Swedish Kronor-USDollar Exchange Rate

Figure 10: DM Statistics across Different Window Sizes of Equations (5) and (10) for the Swiss Franc-USDollar Exchange Rate

8. Conclusion

Although exchange rates are very important, it is not yet possible to perform reliable

forecasts. A solution for this puzzle of the economics profession could be to incorporate

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a time-varying relationship into exchange rate models. For example, Sarno & Valente

(2009) were able to beat the random walk in out-of-sample forecasting if they chose the

model with the lowest forecast error out of a selection with all combinations of six different

fundamentals ex-post for every forecast. Here it is examined whether estimating a time-

varying relationship with a Kalman filter model using ex-ante information can improve

forecasting compared to a model with a constant relationship. Using a Taylor rule exchange

rate model, which is found to have promising out-of-sample forecasting abilities for the

short-term (Molodtsova & Papell, 2009; Rossi, 2013), it is possible to further enhance the

forecasting performance if the information used to update the time-varying coefficients is

restricted. This is necessary as classic exchange rate models do not perform badly only

due to a constant relationship between the exchange rate and its fundamentals, but also

because of missing information (Evans & Lyons, 2002). Thus, without the restriction of the

information, the Kalman filter would adjust the coefficients too strongly. We thereby show

that the Kalman filter is still a useful technique for exchange rate forecasting compared to

OLS. We further note for future research that such an adjustment to the calibration could

also improve forecasting with other models which allow for a time-varying relationship as

Markov switching or smooth transition models.

Still, this approach is not able to beat the random walk in forecasting performance so

that the result of Meese & Rogoff (1983) prevails. However, exchange rate models which

incorporate more explanatory information, such as the order flow model of Evans & Lyons

(2002), would allow an improvement of the estimations of the Kalman filter. Until now,

the Kalman filter cannot distinguish whether a high prediction error is due to missing

information or a constant relationship between the exchange rate and the fundamentals.

Thus, with further explanatory information, the restriction on the information used by

the Kalman filter to estimate the time-varying coefficients can be eased as not only the

prediction error is smaller but also because the size of the error is (more) exclusively deter-

mined by the negligence of the time-varying relationship. With this enhanced estimation

of the time-varying coefficients, forecasting accuracy could be improved.

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References

Alba, J., Park, D., & Xie, T. (2015). Predictability of exchange rates with Taylor rule

fundamentals: Evidence from inflation-targeting emerging countries. Emerging Markets

Finance and Trade, Vol. 51 , pp. 714–728.

Bacchetta, P., & Wincoop, E. (2004). A scapegoat model of exchange-rate fluctuations.

American Economic Review , Vol. 94 , pp. 114–118.

Bacchetta, P., Wincoop, E., & Beutler, T. (2010). Can parameter instability explain the

Meese-Rogoff puzzle? In L. Reichlin, & K. West (Eds.), NBER International Seminar

on Macroeconomics . University of Chicago.

Beckmann, J., Belke, A., & Kuhl, M. (2011). The dollar-euro exchange rate and macroeco-

nomic fundamentals: A time-varying coefficient approach. Review of World Economics,

Vol. 147 , pp. 11–40.

Beckmann, J., & Czudaj, R. (2017a). Exchange rate expectations and economic policy

uncertainty. European Journal of Political Economy , Vol. 47 , pp. 148–162.

Beckmann, J., & Czudaj, R. (2017b). Exchange rate expectations since the financial crisis:

Performance evaluation and the role of monetary policy and safe haven. Journal of

International Money and Finance, Vol. 74 , pp. 283–300.

Beckmann, J., & Czudaj, R. (2017c). The impact of uncertainty on professional exchange

rate forecasts. Journal of International Money and Finance, Vol. 73 , pp. 296–316.

Beckmann, J., & Schussler, R. (2016). Forecasting exchange rates under parameter and

model uncertainty. Journal of International Money and Finance, Vol. 60 , pp. 267–288.

Burnside, C., Eichenbaum, M., & Rebelo, S. (2007). The returns to currency speculation

in emerging markets. American Economic Review , Vol. 97 , pp. 333–338.

Canova, F. (1993). Modelling and forecasting exchange rates with a Bayesian time-varying

coefficient model. Journal of Economic Dynamics and Control , Vol. 17 , pp. 223–261.

Carriero, A., Kapetanios, G., & Marcellino, M. (2009). Forecasting exchange rates with a

large Bayesian VAR. International Journal of Forecasting , Vol. 25 , pp. 400–417.

29

Page 32: Forecasting Exchange Rates - RWI Essen · Forecasting Exchange Rates: The Time-Varying Relationship between Exchange Rates and Taylor Rule Fundamentals Abstract There is empirical

Cheung, Y.-W., Chinn, M., & Pascual, A. (2009). Empirical exchange rate models of the

nineties: Are any fit to survive? Journal of International Money and Finance, Vol. 24 ,

pp. 1150–1175.

Chinn, M. (2006). The (partial) rehabilitation of interest rate parity in the floating rate

era: Longer horizons, alternative expectations, and emerging markets. Journal of Inter-

national Money and Finance, Vol. 25 , pp. 7–21.

Chinn, M. (2009). Comment on: Can parameter instability explain the Meese-Rogoff puz-

zle? In L. Reichlin, & K. West (Eds.), NBER International Seminar on Macroeconomics .

University of Chicago.

Clarida, R., Gali, J., & Gertler, M. (1998). Monetary rules in practice: Some international

evidence. European Economic Review , Vol. 42 , pp. 1033–1067.

Clark, T., & McCracken, M. (2001). Tests of equal forecast accuracy and encompassing

for nested models. Journal of Econometrics , Vol. 105 , pp. 85–110.

Clark, T., & McCracken, M. (2005). Evaluating direct multistep forecasts. Econometric

Reviews, Vol. 24 , pp. 369–404.

Clark, T., & West, K. (2006). Using out-of-sample mean squared prediction errors to test

the martingale difference hypothesis. Journal of Econometrics , Vol. 135 , pp. 155–186.

Clark, T., & West, K. (2007). Approximately normal tests for equal predictive accuracy

in nested models. Journal of Econometrics , Vol. 138 , pp. 291–311.

Diebold, F., & Mariano, R. (1995). Comparing predictive accuracy. Journal of Business

and Economic Statistics, Vol. 13 , pp. 253–265.

Elliot, G., Granger, C., & Timmermann, A. (2006). Handbook of Economic Forecasting .

Amsterdam: Elsevier.

Engel, C., Mark, N., & West, K. (2007). Taylor rules and the Deutschmark-dollar real

exchange rates. In NBER Macroeconomics Annual .

Engel, C., & West, K. (2005). Exchange rate and fundamentals. In NBER Macroeconomics

Annual .

30

Page 33: Forecasting Exchange Rates - RWI Essen · Forecasting Exchange Rates: The Time-Varying Relationship between Exchange Rates and Taylor Rule Fundamentals Abstract There is empirical

Engel, C., & West, K. (2006). Taylor rules and the Deutschmark-dollar real exchange rates.

Journal of Money, Credit and Banking , Vol. 38 , pp. 1175–1194.

Evans, M., & Lyons, R. (2002). Order flow and exchange rate dynamics. Journal of Political

Economy , Vol. 110 , pp. 170–180.

Fratzscher, M., Sarno, L., & Zinna, G. (2015). The scapegoat theory of exchange rates:

The first tests. Journal of Monetary Economics, Vol. 70 , pp. 1–21.

Giannone, D. (2009). Comment on: Can parameter instability explain the Meese-Rogoff

puzzle? In L. Reichlin, & K. West (Eds.), NBER International Seminar on Macroeco-

nomics . University of Chicago.

Gourinchas, P.-O., & Rey, H. (2007). International financial adjustment. Journal of Poli-

tical Economy , Vol. 115 , pp. 665–703.

Gourinchas, P.-O., & Tornell, A. (2004). Exchange rate puzzles and distorted beliefs.

Journal of International Economics, Vol. 64 , pp. 303–333.

Hodrick, R., & Prescott, E. (1997). Postwar U.S. business cycles: An empirical investiga-

tion. Journal of Money, Credit, and Banking , Vol. 29 , pp. 1–16.

Inoue, A., & Rossi, B. (2012). Out-of-sample forecast tests robust to the choice of window

size. Journal of Business and Economics Statistics, Vol. 30 , pp. 432–453.

Kalman, R. (1960). A new approach to linear filtering and prediction problems. Journal

of Basic Engineering , Vol. 83 , pp. 35–45.

Lansing, K., & Ma, J. (2015). Explaining exchange rate anomalies in a model with Taylor

rule fundamentals and consistent expectations. Working Paper No. 22 Federal Reserve

Bank of San Francisco.

Mark, N. (2009). Changing monetary policy rules, learning, and real exchange rate dyna-

mics. Journal of Money, Credit and Banking , Vol. 41 , pp. 1047–1070.

Meese, R., & Rogoff, K. (1983). Empirical exchange rate models of the Seventies: Do they

fit out of the sample? Journal of International Economics, Vol. 41 , pp. 3–24.

Mishkin, F. (2004). The economics of money, banking and financial markets. (Seventh

ed.). London: Pearson.

31

Page 34: Forecasting Exchange Rates - RWI Essen · Forecasting Exchange Rates: The Time-Varying Relationship between Exchange Rates and Taylor Rule Fundamentals Abstract There is empirical

Molodtsova, T., Nikolsko-Rzhevskyy, A., & Papell, D. (2008). Taylor rules with real-time

data: A tale of two countries and one exchange rate. Journal of Monetary Economics,

Vol. 55 , pp. 167–180.

Molodtsova, T., & Papell, D. (2009). Out-of-sample exchange rate predictability with

Taylor rule fundamentals. Journal of International Economics, Vol. 77 , pp. 435–443.

Newey, W., & West, K. (1994). Automatic lag selection in covariance matrix estimation.

Review of Economic Studies, Vol. 61 , pp. 631–654.

Ng, P., & Heidari, A. (2008). Forecast comparison of exchange rate models with the Kalman

filter. Technological Forecasting and Social Change, Vol. 41 , pp. 435–443.

Orphanides, A. (2001). Monetary policy rules based on real-time data. American Economic

Review , Vol. 91 , pp. 964–985.

Orphanides, A., & van Norden, S. (2002). The unreliability of output gap estimates in real

time. Review of Economics and Statistics, Vol. 84 , pp. 569–583.

Rogoff and Stavrakeva (2008). The continuing puzzle of short horizon exchange rate fore-

casting . NBER Working Papers No. 14071, National Bureau of Economic Research.

Rossi, B. (2006). Are exchange rates really random walks? Some evidence robust to

parameter instability. Macroeconomic Dynamics, Vol. 10 , pp. 20–38.

Rossi, B. (2013). Exchange rate predictability. Journal of Economic Literature, Vol. 51 ,

pp. 1063–1119.

Sarno, L., & Valente, G. (2009). Exchange rates and fundamentals: Footloose or evolving

relationship? Journal of the European Economic Association, Vol. 7 , pp. 786–830.

Schinasi, G., & Swamy, P. (1987). The out-of-sample forecasting performance of exchange

rate models when coefficients are allowed to change. Journal of International Money and

Finance, Vol. 8 , pp. 375–390.

Stock, J., & Watson, M. (1996). Evidence on structural instability in macroeconomic time

series relations. Journal of Business and Economic Statistics, Vol. 14 , pp. 11–30.

Taylor, J. (1993). Discretion versus policy rules in practice. In Carnegie-Rochester Confe-

rence Series on Public Policy, Vol. 39 (pp. 195–214).

32

Page 35: Forecasting Exchange Rates - RWI Essen · Forecasting Exchange Rates: The Time-Varying Relationship between Exchange Rates and Taylor Rule Fundamentals Abstract There is empirical

Wang, J., & Wu, J. (2012). The Taylor rule and forecast intervals for exchange rates.

Journal of Money, Credit and Banking , Vol. 44 , pp. 103–144.

Wolff, C. (1987). Time-varying parameters and the out-of-sample forecasting performance

of structural exchange rate models. Journal of Business and Economic Statistics, Vol.

5 , pp. 87–97.

Yuksel, E., Metin-Ozcan, K., & Hatipoglu, O. (2013). A survey on time-varying parameter

Taylor rule: A model modified with interest rate pass-through. Economic Systems, Vol.

37 , pp. 122–134.

33